Method and system for hybrid cooling systems

ABSTRACT

Systems and methods are provided for a hybrid cooling system is provided that includes a load center with a load center inlet and a load center outlet. The system also includes a condenser that has a condenser inlet and a condenser outlet. The load center outlet is fluidically coupled to the condenser inlet. The system further includes a cooling tower that has a cooling tower inlet and a cooling tower outlet. The condenser outlet is fluidically coupled to the cooling tower inlet. The system includes an evaporator that has an evaporator inlet and an evaporator outlet. The cooling tower outlet is fluidically coupled to the evaporator inlet, and the evaporator outlet is fluidically coupled to the load center inlet.

PRIORITY CLAIM

This application claims priority under 35 U.S.C. §119 to U.S. Provisional Patent Application Ser. No. 61/808,091 filed Apr. 3, 2013. The contents of which is incorporated by reference herein in its entirety.

TECHNICAL FIELD

The present disclosure relates in general to cooling systems for building and process load centers, and more particularly to hybrid cooling systems and associated methods.

BACKGROUND

Generally, cooling systems for industrial, computing, commercial, residential, and other load centers are designed to maintain environmental standards. For example, modern computer data centers have servers, switches, and networking equipment that are maintained at particular environmental temperature and humidity ranges. As such, data centers use a significant amount of energy to operate, and in fact, data center energy use is one of the fastest growing segments of energy consumption in the United States. This fact may be driving data centers, especially large data centers, to find and use more energy efficient methods and systems.

One way in which industrial, computing, and commercial centers may become more energy efficient may be through increasing the efficiency of associated cooling systems. Conventional cooling systems may include a chiller, direct expansion gas cooling, water-side economizer, air-side economizer, or some combination of these components. In addition, conventional cooling systems often utilize water or glycol as a cooling medium in closed loop systems. Alternatively, conventional cooling systems may utilize room air cooling units, for example, placed near the server racks in a data center. In these systems, cooling may be accomplished by the operation of a direct expansion system, a water-side economizer system, or the circulation of chilled water or in some cases glycol as a cooling medium in closed loop systems.

Cooling systems, such as a free cooling system or a double loop cooling system, may be designed to operate in a variety of cooling scenarios and conditions including some conditions that may exist for only a small fraction of the required cooling time in a given year. Additionally, transitioning between types of cooling systems, such as a free cooling system and a double loop cooling system, may be cumbersome and difficult to achieve.

SUMMARY

In accordance with the teachings of the present disclosure, disadvantages and problems associated with free cooling systems, double loop cooling systems, and transitions between cooling systems may be substantially reduced or eliminated.

In accordance with one embodiment of the present disclosure, a hybrid cooling system is provided that includes a load center with a load center inlet and a load center outlet. The system also includes a condenser that has a condenser inlet and a condenser outlet. The load center outlet is fluidically coupled to the condenser inlet. The system further includes a cooling tower that has a cooling tower inlet and a cooling tower outlet. The condenser outlet is fluidically coupled to the cooling tower inlet. The system includes an evaporator that has an evaporator inlet and an evaporator outlet. The cooling tower outlet is fluidically coupled to the evaporator inlet, and the evaporator outlet is fluidically coupled to the load center inlet.

In accordance with another embodiment of the present disclosure, a cooling system is provided that includes a load center with a load center inlet and a load center outlet. The system further includes a condenser that has a condenser inlet and a condenser outlet, and a cooling tower that has a cooling tower inlet and a cooling tower outlet. The system also includes an evaporator that has an evaporator inlet and an evaporator outlet. The system includes a temperature sensor configured to measure a temperature of a first coolant that exits the cooling tower outlet. Based on the measured temperature being greater than a first designed temperature, the system includes that the first coolant is directed from the load center outlet to the condenser inlet, and from the condenser outlet to the cooling tower inlet. The first coolant is further directed from the cooling tower outlet to the evaporator inlet, and from the evaporator outlet to the load center inlet. Based on the measured temperature being less than or equal to the first designed temperature, the system includes that the first coolant is directed from the load center outlet to the cooling tower inlet, and from the cooling tower outlet to the load center inlet.

In accordance with another embodiment of the present disclosure, a method is provided for a cooling system that includes measuring a cooling tower exit temperature of a first coolant. Based on the measured temperature being greater than a first designed temperature, the method includes directing the first coolant from a load center outlet to a condenser inlet, from a condenser outlet to a cooling tower inlet, from a cooling tower outlet to an evaporator inlet, and from an evaporator outlet to a load center inlet. Based on the measured temperature being less than or equal to the first designed temperature, the method further includes directing the first coolant from the load center outlet to the cooling tower inlet, and from the cooling tower outlet to the load center inlet.

Other technical advantages will be apparent to those of ordinary skill in the art in view of the following specification, claims, and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present embodiments and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features, and wherein:

FIG. 1 illustrates an example block diagram of an exemplary cooling configuration that includes a free cooling system, a hybrid cooling system, and a double loop cooling system, in accordance with certain embodiments of the present disclosure;

FIG. 2 illustrates an example block diagram of an exemplary cooling configuration that includes a free cooling system and a hybrid cooling system, in accordance with certain embodiments of the present disclosure;

FIG. 3 illustrates an example psychometric chart showing an exemplary cooling process utilizing a hybrid cooling system, in accordance with certain embodiments of the present disclosure; and

FIG. 4 illustrates a flow chart for an example method for cooling system transitions using hybrid cooling systems, in accordance with certain embodiments of the present disclosure.

DETAILED DESCRIPTION

Preferred embodiments and their advantages are best understood by reference to FIGS. 1-4, wherein like numbers are used to indicate like and corresponding parts.

FIG. 1 illustrates an example block diagram of exemplary cooling configuration 100 that includes free cooling system 102, hybrid cooling system 104, and double loop cooling system 106, in accordance with certain embodiments of the present disclosure. Cooling configuration 100 may be utilized to cool load center 118. Design and specifications relating to cooling configuration 100 may be based on a target environment for load center 118, which may include a designed or target temperature and a designed or target humidity. Based on the target environment for load center 118 and the amount of heat generated in load center 118, the incoming coolant temperature may be specified. The specified incoming coolant temperature may be based in part on the output of any air-handlers providing air flow to load center 118. As an example, a large data center may create an approximately 800 ton load and require a target ambient air temperature between approximately sixty-one and seventy-five degrees Fahrenheit and a humidity range of approximately forty to fifty-five percent. This may be achieved by providing local cooling systems, such as a data center with chilled coolant. For example, based on the target environment for load center 118, the specified incoming coolant temperature may be approximately fifty-five degrees Fahrenheit. Efforts focused at energy efficient cooling systems have included developments in cooling systems that do not incorporate a chiller (U.S. Pub. No. 2011/0225997) and using multiple coolants with multiple loops (U.S. Pat. No. 6,257,007).

Cooling configuration 100 may include cooling system 180 and/or processing system 126. Cooling system 180 may include different cooling subsystems or modes of cooling. For example, cooling system 180 may include free cooling system 102 with a coolant flow shown by a dotted line. Cooling system 180 may further include hybrid cooling system 104 with a coolant flow shown by a solid line. Additionally, cooling system 180 may include double loop cooling system 106 a and 106 b (collectively referred to as double loop cooling system 106) with coolant flows shown by a dash-dot line.

Additionally, coolant, e.g., cooling water 124 or secondary fluid 146, circulates through cooling system 180 is at various temperatures at different sections of cooling system 180. Temperature measurement may be accomplished by temperature sensors placed and configured to measure cooling water 124 and/or exterior temperatures or wet bulb temperatures as suitable for a specific implementation. For explanatory purposes, four relative temperature ranges (TR) are specified. Each temperature range specified is not absolute, but relative to the other temperature ranges. For example, TR_(A) may represent the coldest temperature range. TR_(B) may represent a cool temperature range. TR_(C) may represent a warm temperature range. TR_(D) may represent a hot temperature range. For example, TR_(A) may correspond to temperatures approximately fifty-five degrees Fahrenheit or lower, TR_(B) may correspond to temperatures approximately fifty-six to sixty-five degrees Fahrenheit, TR_(C) may correspond to temperatures approximately sixty-six to seventy-five degrees Fahrenheit, and TR_(D) may correspond to temperatures approximately seventy-six degrees Fahrenheit or higher.

Cooling system 180 may include cooling tower 108, one or more tower pumps 110, filtration subsystem 112, one or more tower valves 114, chiller subsystem 116, load center 118, one or more center valves 120, and/or one or more system pumps 122. Components of cooling system 180 may be fludically coupled. Cooling system 180 may include piping sections through which a fluid circulates and that may connect components making up free cooling system 102, hybrid cooling system 104, and/or double loop cooling system 106. Although shown as three separate flows, fluid flowing through free cooling system 102, hybrid cooling system 104, and/or double loop cooling system 106 may be contained in the same pipe and/or piping structure and may, as will be described herein, confine the same fluid in a continuous flow.

In some embodiments, free cooling system 102 includes cooling water 124 that circulates through a single loop of piping, machinery, and/or other connections. Free cooling system 102 may circulate cooling water 124 through cooling tower 108, tower pumps 110, filtration subsystem 112, tower valves 114, load center 118, and/or center valves 120. Free cooling system 102 may further include a chemical treatment and monitoring subsystem, a temperature control subsystem, and/or a mechanical cooling subsystem. Free cooling system 102 may be open to the exterior environment at cooling tower 108.

Cooling water 124 circulating in free cooling system 102 exits cooling tower 108 through cooling tower outlet 158 in temperature range TR_(A). Cooling water 124 that exits cooling tower 108 may be at temperature T_(CT). For example, cooling water 124 in free cooling system 102 may exit cooling tower 108 at T_(CT) equal to approximately fifty-five degrees Fahrenheit. Cooling water 124 circulates through tower pump 110, filtration subsystem 112, and tower valves 114 to load center inlet 168 at approximately the same temperature, e.g. T_(CT). Cooling water 124 is heated a defined number of degrees, e.g. ΔT_(L), while circulating through load center 118. For example, cooling water 124 may be heated a ΔT_(L) equal to approximately ten degrees Fahrenheit as a result of the desired removal of heat from load center 118. Thus, in the current example, cooling water 124 exiting load center 118 at load center outlet 162 may be in temperature range TR_(B) or temperature equal to approximately sixty-five degrees Fahrenheit. Cooling water 124 circulates though center valves 120 and back to cooling tower 108 to enter cooling tower inlet 160 in temperature range TR_(B) or temperature approximately sixty-five degrees Fahrenheit in the current example. Cooling water 124 circulating in free cooling system 102 circulates through cooling tower 108 and the temperature of cooling water 124 may be lowered by ΔT_(L). For example, cooling water 124 exiting cooling tower 108, e.g. T_(CT), may again be in temperature range TR_(A) or approximately fifty-five degrees Fahrenheit. A ΔT_(L) of approximately ten degrees Fahrenheit may be for ease of example and a cooling system design may account for larger or smaller ΔT_(L) and different inlet and exit temperatures as suitable for a particular implementation.

In some embodiments, cooling system 180 may be configured to operate free cooling system 102 below a target wet bulb temperature, e.g., low humidity atmospheric air. For example, at a wet bulb temperature below approximately fifty degrees Fahrenheit, free cooling system 102 may be the more efficient cooling system to operate instead of either double loop cooling system 106 or hybrid cooling system 104. However, as the wet bulb temperature rises, free cooling system 102 may not be capable of lowering the temperature of cooling water 124 sufficiently to adequately cool load center 118. For example, cooling tower 108 operating alone, e.g., without the use of chiller 116, may be unable to lower the temperature of cooling water 124 to approximately fifty-five degrees Fahrenheit that may be required to adequately cool load center 118. Thus, cooling system 180 may be configured to transition from free cooling system 102 to either double loop cooling system 106 or hybrid cooling system 104 when the atmospheric conditions and/or the temperature of cooling water 124 indicate that free cooling system 102 is no longer adequately lowering the temperature of cooling water 124.

In some embodiments, cooling system 180 may include double loop cooling system 106. Double loop cooling system 106 may include first loop 106 a and secondary loop 106 b. The inclusion of secondary loop 106 b may allow the use of coolant or secondary fluid 146 that may be circulated separately from cooling water 124. Secondary fluid 146 may be the medium that cools load center 118 in the case that free cooling system 102 and/or hybrid cooling system 104 is unable to adequately lower the temperature of cooling water 124. However, as will be discussed herein, if hybrid cooling system 104 is to be used, the same coolant, e.g., cooling water 124, would be used throughout.

First loop 106 a may include cooling water 124 that circulates through a loop of piping, machinery, and/or other connections. First loop 106 a may circulate cooling water 124 through cooling tower 108, tower pumps 110, filtration subsystem 112, tower valves 114, and/or condenser 138. Second loop 106 b may include secondary fluid 146. Secondary fluid 146 may be water, glycol, Freon, refrigerant, and/or any other suitable cooling fluid. Second loop 106 b may circulate secondary fluid 146 through evaporator 136, load center 118, center valves 120, and/or system pumps 122.

Cooling water 124 circulating in first loop 106 a exits cooling tower 108 through cooling tower outlet 158 in temperature range TR_(C). Cooling water 124 that exits cooling tower 108 may be at temperature T_(CT). For example, cooling water 124 in first loop 106 a may exit cooling tower 108 at T_(CT) equal to approximately seventy-five degrees Fahrenheit. Cooling water 124 circulates through tower pump 110, filtration subsystem 112, and tower valves 114 to condenser 138 at approximately the same temperature, e.g. T_(CT). Cooling water 124 is heated a defined number of degrees, e.g. ΔT_(C), while circulating through condenser 138. For example, cooling water 124 may be heated a ΔT_(C) equal to approximately ten degrees Fahrenheit. Thus, in the current example, cooling water 124 exiting condenser 138 at condenser outlet 156 may be in temperature range TR_(D) or at temperature equal to approximately eighty-five degrees Fahrenheit. Cooling water 124 circulates back to cooling tower 108 to enter cooling tower inlet 160. Cooling water 124 may enter cooling tower inlet 160 in temperature range TR_(D) or approximately eighty-five degrees Fahrenheit in the current example. Cooling water 124 circulating in first loop 106 a circulates through cooling tower 108 and the temperature of cooling water 124 may be lowered by ΔT_(C). For example, cooling water 124 exiting cooling tower 108, e.g. T_(CT), may again be in temperature range TR_(C) at approximately seventy-five degrees Fahrenheit.

In a second loop of double loop cooling system 106, secondary fluid 146 circulating in second loop 106 b exits evaporator 136 through evaporator outlet 152. Secondary fluid 146 that exits evaporator 136 may be in temperature range TR_(A). For example, secondary fluid 146 in second loop 106 b may exit evaporator 136 approximately fifty-five degrees Fahrenheit. Secondary fluid 146 enters load center inlet 168 and is heated a defined number of degrees, e.g. ΔT_(L), while circulating through load center 118. For example, secondary fluid 146 may be heated a ΔT_(L) equal to approximately ten degrees Fahrenheit. Thus, in the current example, secondary fluid 146 exiting load center 118 at load center outlet 162 may be in temperature range TR_(B) at temperature equal to approximately sixty-five degrees Fahrenheit. Secondary fluid 146 circulates back through center valves 120 and system pump 122 to evaporator 136 to enter evaporator inlet 150 in temperature range TR_(B) or approximately sixty-five degrees Fahrenheit in the current example. Secondary fluid 146 circulating in second loop 106 b circulates through evaporator 136 and the temperature of secondary fluid 146 may be lowered by ΔT_(L). For example, secondary fluid 146 exiting evaporator 136 may again be in temperature range TR_(A) or approximately fifty-five degrees Fahrenheit.

It should be noted that double loop cooling system 106 may require additional pumps, e.g., system pumps 122, in comparison to free cooling system 102 and hybrid cooling system 104 in order to separately circulate the separate fluids through first and second loops 106 a and 106 b. Also, double loop cooling system 106 may employ a chiller 116 including evaporator 136 and condenser 138 to provide additional cooling. The use of chiller 116 may allow double loop cooling system 106 to operate in environments with higher temperatures, higher humidity levels and/or higher wet bulb temperatures than free cooling system 102. As such, double loop cooling system 106 may have higher energy requirements than free cooling system 102. Thus, reductions in energy consumption may be achieved by operating cooling system 180 as free cooling system 102 when environmental conditions allow and only operate double loop cooling system 106 when necessary.

However, transitioning between free cooling system 102 and double loop cooling system 106 may be difficult, cumbersome, and/or involve reliability risks. In operation, chiller 116 may require a designed lift, or temperature difference, to be present across chiller 116 in order for chiller 116 to operate. Generally, the lower the lift, the more efficient chiller 116 may operate. However, the chiller design may require that the minimum lift between the condenser outlet 156 and the evaporator outlet 152 be approximately ten degrees Fahrenheit. If the designed lift is not present, chiller 116 may be difficult to start and/or operate and in particular designs, chiller 116 may not start and/or operate without the designed lift present. When a transition between free cooling system 102 and double loop cooling system 106 begins, the required lift may not be present. Thus, artificial loads and other methods of artificially generating the required lift, or temperature difference, may have to be employed. Artificial loads may add to the energy consumption and may reduce the overall efficiency of cooling system 180. Consequently, transitioning between free cooling system 102 and double loop cooling system 106 may be difficult and may require artificial loads to be generated and placed on chiller 116 until the required lift is achieved. The incorporation and utilization of hybrid cooling system 104 may provide an intermediate cooling solution and may alleviate the difficulty of cooling system transitions. This will prevent inefficiencies associated with artificial loads and generate overall energy savings.

Hybrid cooling system 104 may utilize the same components described previously with a different flow pattern to provide a third modality for cooling that may operate in a domain between free cooling system 102 and double loop cooling system 106. In some embodiments, hybrid cooling system 104 includes cooling water 124 that circulates through a single loop of piping, machinery, and/or other connections. Hybrid cooling system 104 may circulate cooling water 124 through cooling tower 108, tower pumps 110, filtration subsystem 112, tower valves 114, evaporator 136, load center 118, center valves 120, and/or condenser 138.

Cooling water 124 circulating in hybrid cooling system 104 exits cooling tower 108 through cooling tower outlet 158 in temperature range TR_(B). Cooling water 124 that exits cooling tower 108 may be at temperature T_(CT). For example, cooling water 124 in hybrid cooling system 104 may exit cooling tower 108 at T_(CT) equal to approximately sixty degrees Fahrenheit. Cooling water 124 may circulate through tower pump 110, filtration subsystem 112, and tower valves 114 to evaporator 136 at evaporator inlet 150 at approximately the same temperature, e.g. T_(CT). As cooling water 124 circulates through evaporator 136, cooling water 124 is cooled a defined number of degrees, e.g. ΔT_(C). For example, cooling water 124 may be cooled a ΔT_(C) equal to approximately five degrees Fahrenheit to a temperature of approximately fifty-five degrees Fahrenheit in temperature range TR_(A). Cooling water 124 may exit evaporator 136 at evaporator outlet 152 and circulate to load center 118 while maintaining approximately the same temperature. Cooling water 124 is heated ΔT_(L) as it circulates in load center 118. Thus, in the current example, cooling water 124 exiting load center 118 at load center outlet 162 may be in temperature range TR_(B) or temperature equal to approximately sixty-five degrees Fahrenheit. Cooling water 124 circulates though center valves 120 and to condenser 138 to enter condenser inlet 154. Cooling water 124 is heated ΔT_(C) while circulating through condenser 138. For example, cooling water 124 may be heated a ΔT_(C) equal to approximately five degrees Fahrenheit. Thus, in the current example, cooling water 124 exiting condenser 138 at condenser outlet 156 may be in temperature range TR_(C) or temperature equal to approximately seventy degrees Fahrenheit. Cooling water 124 may circulate back to cooling tower 108 to enter cooling tower inlet 160 in temperature range TR_(C) or temperature approximately seventy degrees Fahrenheit in the current example. Cooling water 124 circulating in hybrid cooling system 104 circulates through cooling tower 108 and the temperature of cooling water 124 may be lowered by ΔT_(L). For example, cooling water 124 exiting cooling tower 108, e.g. T_(CT), may again be in temperature range TR_(B) or approximately sixty degrees Fahrenheit.

In some embodiments, hybrid cooling system 104 may resolve issues associated with starting chiller 116 as discussed with reference to double loop cooling system 106. In contrast to double loop cooling system 106, hybrid cooling system 104 is configured to direct cooling water 124 from tower valves 114 to evaporator inlet 150 rather than condenser inlet 154. In hybrid cooling system 104, the temperature of cooling water 124 at evaporator inlet 150 may be approximately the same temperature as the temperature at cooling tower outlet 158, e.g., T_(CT). For example, T_(CT) may be approximately sixty degrees Fahrenheit. This configuration may result in lift, or temperature difference across chiller 116, of approximately fifteen degrees Fahrenheit. Thus, in hybrid cooling system 104, the designed lift required across chiller 116 may be created in a single loop. Accordingly, the incorporation of hybrid cooling system 104 in cooling system 180 may provide an intermediate cooling system that may address intermediate environments and allow for less cumbersome transitions between free and double loop cooling configurations. In addition, in this example, the chiller may be running at approximately fifty percent of the design load, thus saving energy.

In some embodiments, use of hybrid cooling system 104 may allow components of cooling system 180 to be sized smaller than required in double loop cooling system 106. For example, the same amount of cooling may be achieved with hybrid cooling system 104 using an approximately 570 ton chiller as may be achieved with double loop cooling system 106 using an approximately 1000 ton chiller.

Components of cooling configuration 100 may include processing system 126. Processing system 126 may include any instrumentality or aggregate of instrumentalities operable to compute, classify, process, transmit, receive, retrieve, originate, switch, store, display, manifest, detect, record, reproduce, handle, or utilize any form of information, intelligence, or data for business, scientific, control, or other purposes. For example, processing system 126 may be a personal computer, a network storage resource, or any other suitable device and may vary in size, shape, performance, functionality, and price.

Processing system 126 may include one or more processing resources such as a central processing unit (CPU), microprocessor, microcontroller, digital signal processor (DSP), application specific integrated circuit (ASIC), or any other digital or analog circuitry configured to interpret and/or execute program instructions and/or process data. A processing resource may interpret and/or execute program instructions and/or process data stored in memory, mass storage device, and/or another component of cooling configuration 100.

Processing system 126 may include any system, device, or apparatus operable to retain program instructions or data for a period of time (e.g., computer-readable media) such as hardware or software control logic, random access memory (RAM), electrically erasable programmable read-only memory (EEPROM), a PCMCIA card, flash memory, magnetic storage, opto-magnetic storage, or any suitable selection and/or array of volatile or non-volatile memory that retains data after power to processing system 126 may be removed.

Processing system 126 may include one or more storage resources (or aggregations thereof) communicatively coupled to the processing resource and may include any system, device, or apparatus operable to retain program instructions or data for a period of time (e.g., computer-readable media). Storage resources may include one or more hard disk drives, magnetic tape libraries, optical disk drives, magneto-optical disk drives, compact disk drives, compact disk arrays, disk array controllers, solid state drives (SSDs), and/or any computer-readable medium operable to store data. Computer-readable media may include any instrumentality or aggregation of instrumentalities that may retain data and/or instructions for a period of time. Computer-readable media may include, without limitation, storage media such as a direct access storage device (e.g., a hard disk drive or floppy disk), a sequential access storage device (e.g., a tape disk drive), compact disk, CD-ROM, DVD, random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), and/or flash memory; as well as communications media such wires, optical fibers, microwaves, radio waves, and other electromagnetic and/or optical carriers; and/or any combination of the foregoing.

Additional components of processing system 126 may include one or more network ports for communicating with external devices as well as various input and output (I/O) devices, such as a keyboard, a mouse, and a video display. Processing system 126 may also include one or more buses or wireless devices operable to transmit communications between the various hardware components and/or any component of cooling system 180.

Processing system 126 may generally be operable to receive data from, and/or transmit data to, any component of cooling system 180 and/or other processing systems. Processing system 126 may be a host computer, a remote system, and/or any other computing system communicatively coupled to cooling system 180. Processing system 126 may be included in load center 118 or may be remote from cooling system 180.

Cooling tower 108 may be a high efficiency counter-flow design with an induced draft fan. In alternate embodiments, cooling tower 108 may utilize other designs and configurations that perform the same or similar function. Cooling tower 108 may use an induced draft fan to draw or blow atmospheric air through an atmospheric air inlet 130. The induced draft fan may be a fixed speed fan or a variable speed fan. Cooling tower 108 may be exposed to the external atmosphere. The atmospheric air may interact with cooling water 124 that enters cooling tower 108 via return piping section 160. As the cooling water 124 exiting the return piping section 160 mixes with the atmospheric air, the latent heat of vaporization is absorbed from cooling water 124 and the atmospheric air. As a result, cooling water 124 is cooled. Cooling tower 108 may additionally include temperature sensors, flow rate meters, pressure sensors, and/or any other suitable components to allow for monitoring and control of cooling tower 108.

The rate and amount of cooling performed within cooling tower 108 will depend on the wet bulb characteristics of the atmospheric air. Generally, the lower the wet bulb temperature of the atmospheric air, e.g., the humidity in the atmospheric air, the more cooling that takes place within cooling tower 108. For example, installation of cooling configuration 100 in geographic locations known to have atmospheric air with low wet bulb temperatures, such as deserts or arid climates, allows for increased cooling or more efficient cooling in cooling tower 108 than an installation of cooling configuration 100 in a geographic area with higher wet bulb temperatures. In arid climates, cooling tower 108 may cool cooling water 124 to within three to five degrees Fahrenheit of the wet bulb temperature. Thus, the exact efficiencies of cooling tower 108 will vary with atmospheric characteristics.

After the atmospheric air is cooled within cooling tower 108, the atmospheric air may be exhausted to the atmosphere through atmospheric air exhaust 132 included in cooling tower 108. In some embodiments, atmospheric air exhaust 132 may be located in cooling tower 108 opposite from atmospheric air inlet 130 to form a defined flow path of atmospheric air through cooling tower 108. In alternate embodiments, the location of atmospheric air exhaust 132 may vary. Just as the atmospheric air exhausts from cooling tower 108, cooling water 124 that has been cooled, may also exit cooling tower 108 at cooling tower outlet 158.

In some embodiments, cooling tower 108 may be fluidically connected or coupled via piping to tower pumps 110. After the cooling water 124 is cooled in cooling tower 108, cooling water 124 accumulates within cooling tower 108 and tower pumps 110 pumps cooling water 124 through tower pumps 110. Tower pumps 110 may include one or more pumps in various configurations. For example, tower pumps 110 may be configured in parallel or may be configured such that one pump may be designated as an operating tower pump while additional pumps may be designated as a standby pump. Thus, the operating pump normally pumps cooling water 124, while the standby pump remains in standby in case the operating pump fails or another system condition requires the use of the standby pump. In alternate embodiments, tower pumps 110 may be configured in series or a single pump may be utilized.

Tower pumps 110 may be variable speed, thus allowing variable flow and/or pressure, or fixed speed pumps. Tower pumps 110 may be configured to maintain a consistent flow such as gallons per minute (GPM). Further, tower pumps 110 may be particular horsepower (hp) pumps. For example, tower pumps 110 may include one pump configured to operate at fifty hp and generate a flow of 1,300 GPM. Tower pumps 110 may additionally include temperature sensors, flow rate meters, pressure sensors, and/or any other suitable components to allow for monitoring and control of tower pumps 110.

Tower pumps 110 may be used to circulate cooling water 124 through various components and subsystems of cooling system 180. Tower pumps 110 may be fluidically connected or coupled via piping to filtration subsystem 112. In some embodiments, tower pumps 110 may additionally be connected via piping to a chemical treatment and monitoring subsystem. In such a configuration, piping connects the chemical treatment and monitoring subsystem to filtration subsystem 112 such that at least a portion of cooling water 124 circulates through the chemical treatment and monitoring subsystem prior to entering filtration subsystem 112. The portion of cooling water that enters the chemical treatment and monitoring subsystem may be controlled by one or more valves. The valves may be electronically controlled and coupled with other devices, such as flow rate meters, to direct substantially exact portions of the cooling water 124 to the chemical treatment and monitoring subsystem in order to maintain consistent chemical properties in the cooling water 124. The chemical treatment and monitoring subsystem may chemically treat cooling water 124 to maintain an optimum water chemistry. Additionally, a dedicated chemical subsystem pump or alternate pressure source may circulate the portion of cooling water 124 that enters the chemical treatment and monitoring subsystem.

Tower pumps 110 may circulate cooling water 124 to enter filtration subsystem 112 either directly or once cooling water 124 or a portion of cooling water 124 may be processed through the chemical treatment and monitoring subsystem. Filtration subsystem 112 filters cooling water 124 before it enters tower valve 114 a. Filtration subsystem 112 may include, by way of example only, media filters, screen filters, disk filters, slow sand filter beds, rapid sand filters and cloth filters configured to filter various sizes of particles from cooling water 124. In some embodiments, filtration subsystem 112 will substantially prevent a particle of a predetermined size or larger from circulating with cooling water 124 through the portion of cooling system 180 following filtration subsystem 112. Filtration subsystem 112 may additionally include temperature sensors, flow rate meters, pressure sensors, and/or any other suitable components to allow for monitoring and control of filtration subsystem 112.

Once cooling water 124 passes through filtration subsystem 112, cooling water 124 may enter one or more tower valves 114. Depending on the configuration of tower valves 114, cooling water 124 will be directed to chiller subsystem 116 or to data center 118. Tower valves 114 configuration, and thus direction of cooling water 124, will be based on the cooling system selected: free cooling system 102, hybrid cooling system 104, or double loop cooling system 106. Tower valves 114 may include one or more two-way or three-way valves 164 a and 164 b to direct the flow of cooling water 124. Tower valves 114 may be electronically controlled and coupled with other devices, such as flow rate meters, to direct cooling water 124. Tower valves 114 may additionally include temperature sensors, flow rate meters, pressure sensors, and/or any other suitable components to allow for monitoring and control of tower valves 114.

In some embodiments, chiller subsystem or chiller 116 may be utilized to further chill cooling water 124 in both hybrid cooling system 104 and double loop cooling system 106. Chiller 116 may include evaporator 136 and condenser 138. Condenser 138 may be configured to absorb heat from either cooling water 124 or secondary fluid 146 flowing through evaporator 136. Condenser 138 may include motors, fans, compressors, and/or any other suitable machinery operable for absorbing heat and continuously providing cooling to fluid traversing evaporator 136. Condenser 138 may additionally include temperature sensors, flow rate meters, pressure sensors, and/or any other suitable components to allow for monitoring and control of condenser 138.

Evaporator 136 may be configured to work in connection with condenser 138. Evaporator 136 may condition cooling water 124 or secondary fluid 146 to a predetermined temperature, such as approximately fifty-five degrees Fahrenheit. Cooling water 124 or secondary fluid 146 may enter evaporator 136 at evaporator inlet 150. Cooling water 124, as part of hybrid cooling system 104, enters evaporator from filtration subsystem 112 and tower valves 114. Cooling water 124 may be at a warm temperature, such as approximately sixty-five degrees Fahrenheit. As another example, secondary fluid 146 as part of secondary loop 106 b in double loop cooling system 106 may enter evaporator from load center 118 at a warm temperature of approximately sixty-five degrees Fahrenheit. Evaporator 136 may additionally include temperature sensors, flow rate meters, pressure sensors, and/or any other suitable components to allow for monitoring and control of evaporator 136.

Load center 118 may include any equipment and/or machinery that generates heat during operation. For example, load center 118 may include computing data center that may contain multiple computing systems, an industrial or manufacturing center, a hospital, a school, a residence or residential facility, and/or any other systems, buildings, or facilities that generate heat during operation. Load center 118 may be designed to maintain a particular environment for the protection of equipment and/or machinery included in load center 118 and/or for the comfort of personnel in load center 118. For example, load center 118 may be a data center that may be designed to maintain a temperature of approximately fifty-five degrees Fahrenheit and a humidity level below a certain threshold, such as approximately fifty percent. Load center 118 may additionally include temperature sensors, flow rate meters, pressure sensors, and/or any other suitable components to allow for monitoring and control of load center 118.

In some embodiments, load center 118 may include multiple air-handler units 140, and/or humidification elements 142. Generally, air-handler units 140 may provide an interface between cooling water 124 cooled by cooling tower 108 and/or chiller 116 and load air 144 that may have been heated in load center 118. For example, load air 144 may be heated by the operation of computing centers in a data center. Load air 144 may be moved into air-handler units 140 through ducting. Cooling water 134 may enter load center 118 via piping, e.g., a cooling coil, that directs cooling water 134 proximate to the air-handler units and/or the heated data center air. As cooling water 134 passes proximate to the air-handling units and/or the heated data center air, the air-handling units may cause the heat in the data center air to transfer to cooling water 134. For example, air-handling units in the form of fans may blow the data center air across the piping that contains cooling water 134. Thus, cooling water 134 that exits data center 118 may be at a higher temperature than cooling water 134 that enters data center 118. The data center air that has been cooled may be directed by the air-handling units back through data center 118. Cooling water 134, which has been heated, may be directed via piping to center valves 120.

The humidity of the data center air may be controlled by humidification element 142. For example, if the humidity level needs to be increased to maintain the correct environment, humidification element 142 may inject water into ducting as load air 144 enters air-handler units 140. In alternate embodiments, the humidity of the data center air could be controlled through use of an evaporative media section, or directly in load center 118.

In some embodiments, cooling water 124 may exit load center 118 and enter one or more center valves 120. Depending on the configuration of center valves 120, cooling water 124 may be directed to chiller 116, system pumps 122, or cooling tower 108. Center valves 120 configuration, and thus direction of cooling water 124, will be based on the cooling system selected: free cooling system 102, hybrid cooling system 104, or double loop cooling system 106. Center valves 120 may include one or more two-way or three-way valves 166 a and 166 b to direct the flow of cooling water 124. Center valves 120 may additionally include temperature sensors, flow rate meters, pressure sensors, and/or any other suitable components to allow for monitoring and control of center valves 120.

In some embodiments, double loop cooling system 106 may require utilizing one or more system pumps 122. System pumps 122 may include one or more pumps in various configurations. For example, system pumps 122 may be configured in parallel or may be configured such that one pump may be designated as an operating system pump while an additional pump may be designated as a standby pump. Thus, the operating pump normally pumps cooling water 124, while the standby pump remains in standby in case the operating pump fails or another system condition requires the use of the standby pump. In alternate embodiments, system pumps 122 may be configured in series or a single pump may be utilized. System pumps 122 may also require a freeze protection subsystem to prevent damage if the pumps are exposed to temperatures below approximately thirty-two degrees Fahrenheit. System pumps 122 may additionally include temperature sensors, flow rate meters, pressure sensors, and/or any other suitable components to allow for monitoring and control of system pumps 122. System pumps 122 may be variable speed, thus allowing variable flow and/or pressure, or fixed speed pumps.

In some embodiments, cooling configuration 100 may be implemented in environments that may be likely to experience extremes in both temperature and humidity. For example, areas in the United States such as Atlanta, Ga. or Houston, Tex. may experience both high humidity and high temperatures for a certain number of hours each year. The most efficient cooling system in such areas may be a cooling system configured similar to cooling configuration 100, e.g., including free cooling system 102, hybrid cooling system 104, and double loop cooling system 106. However, in drier climates that have a lower average wet bulb temperature, such as Denver, Colo., a cooling configuration that may not include double loop cooling system 106 may be more efficient.

FIG. 2 illustrates an example block diagram of exemplary cooling configuration 200 that includes free cooling system 102 and hybrid cooling system 104, in accordance with certain embodiments of the present disclosure. Cooling configuration 200 may be similar to cooling configuration 100 shown in FIG. 1. However, cooling configuration 200 includes cooling system 280 that further includes free cooling system 102 and hybrid cooling system 104. Cooling system 280 may eliminate system pumps, such as system pump 122, that might have been required in cooling system 180 of FIG. 1.

Cooling system 280 may include cooling tower 108, one or more tower pumps 110, filtration subsystem 112, one or more tower valves 114, chiller 116, load center 118, and/or one or more center valves 120. Components of cooling system 280 may be fluidically coupled. Cooling system 280 may include piping sections through which a fluid circulates and that may connect components making up free cooling system 102 and/or hybrid cooling system 104. Although shown as two separate flows, fluid flowing through free cooling system 102 and/or hybrid cooling system 104 may be contained in the same pipe and/or piping structure.

In some embodiments, free cooling system 102 may include cooling water 124 that circulates through a single loop of piping, machinery, and/or other connections. Free cooling system 102 may circulate cooling water 124 through cooling tower 108, tower pumps 110, filtration subsystem 112, tower valves 114, load center 118, and/or center valves 120. Free cooling system 102 may further include a chemical treatment and monitoring subsystem, a temperature control subsystem, and/or a mechanical cooling subsystem. Free cooling system 102 may be open to the exterior environment at cooling tower 108.

Cooling water 124 circulating in free cooling system 102 exits cooling tower 108 through cooling tower outlet 158 in temperature range TR_(A). Cooling water 124 that exits cooling tower 108 may be at temperature T_(CT). For example, cooling water 124 in free cooling system 102 may exit cooling tower 108 at approximately T_(CT) equal to approximately fifty-five degrees Fahrenheit. Cooling water 124 circulates through tower pump 110, filtration subsystem 112, and tower valves 114 to load center inlet 168 at approximately the same temperature, e.g. T_(CT). Cooling water 124 is heated a defined number of degrees, e.g. ΔT_(L), while circulating through load center 118. For example, cooling water 124 may be heated a ΔT_(L) equal to approximately ten degrees Fahrenheit as a result of the desired removal of heat from load center 118. Thus, in the current example, cooling water 124 exiting load center 118 at load center outlet 162 may be in temperature range TR_(B) or temperature equal to approximately sixty-five degrees Fahrenheit. Cooling water 124 circulates though center valves 120 and back to cooling tower 108 to enter cooling tower inlet 160 in temperature range TR_(B) or temperature approximately sixty-five degrees Fahrenheit in the current example. Cooling water 124 circulating in free cooling system 102 circulates through cooling tower 108 and the temperature of cooling water 124 may be lowered by ΔT_(L). For example, cooling water 124 exiting cooling tower 108, e.g. T_(CT), may again be in temperature range TR_(A) or approximately fifty-five degrees Fahrenheit.

In some embodiments, cooling system 280 may also include hybrid cooling system 104. Hybrid cooling system 104 includes cooling water 124 that circulates through a single loop of piping, machinery, and/or other connections. In operation, hybrid cooling system 104 may circulate cooling water 124 through cooling tower 108, tower pumps 110, filtration subsystem 112, tower valves 114, evaporator 136, load center 118, center valves 120, and condenser 138.

Cooling water 124 circulating in hybrid cooling system 104 exits cooling tower 108 through cooling tower outlet 158 in temperature range TR_(B). Cooling water 124 that exits cooling tower 108 may be at temperature T_(CT). For example, cooling water 124 in hybrid cooling system 104 may exit cooling tower 108 at T_(CT) equal to approximately sixty degrees Fahrenheit. Cooling water 124 circulates through tower pump 110, filtration subsystem 112, and tower valves 114 to evaporator 136 at evaporator inlet 150 at approximately the same temperature, e.g. T_(CT). As cooling water 124 circulates through evaporator 136, cooling water 124 is cooled a defined number of degrees, e.g. ΔT_(C). For example, cooling water 124 may be cooled a ΔT equal to approximately five degrees Fahrenheit to a temperature of approximately fifty-five degrees Fahrenheit in temperature range TR_(A). Cooling water 124 exits evaporator 136 at evaporator outlet 152 and circulates to load center 118 while maintaining approximately the same temperature. Cooling water 124 is heated ΔT_(L) as it circulates in load center 118. ΔT_(L) may be equal to approximately ten degrees Fahrenheit. Thus, in the current example, cooling water 124 exiting load center 118 at load center outlet 162 may be in temperature range TR_(B) or temperature equal to approximately sixty-five degrees Fahrenheit. Cooling water 124 circulates though center valves 120 and to condenser 138 to enter condenser inlet 154. Cooling water 124 is heated ΔT_(C) while circulating through condenser 138. For example, cooling water 124 may be heated a ΔT_(C) equal to approximately five degrees Fahrenheit. Thus, in the current example, cooling water 124 exiting condenser 138 at condenser outlet 156 may be in temperature range TR_(C) or temperature equal to approximately seventy degrees Fahrenheit. Cooling water 124 circulates back to cooling tower 108. Cooling water 124 may enter cooling tower inlet 160 in temperature range TR, or temperature approximately seventy degrees Fahrenheit in the current example. Cooling water 124 circulating in hybrid cooling system 104 circulates through cooling tower 108 and the temperature of cooling water 124 is thus lowered by ΔT_(L). For example, cooling water 124 exiting cooling tower 108, e.g. T_(CT), may again be in temperature range TR_(B) or approximately sixty degrees Fahrenheit.

FIG. 3 illustrates an example psychometric chart 300 showing an exemplary cooling process utilizing a hybrid cooling system, in accordance with certain embodiments of the present disclosure. The psychometric chart illustrates psychometric properties of the exterior air prior to entering cooling systems 180 or 280 shown with reference to FIGS. 1 and 2. Psychometric chart 300 may be based on a system designed to deliver approximately fifty-five degree Fahrenheit cooling water 124 to load center 118, e.g., cooling water 124 supply temperature. Psychometric chart 300 may further be based on a heat load at load center 118 of approximately ten degrees Fahrenheit, e.g., cooling water 124 may heat from approximately fifty-five degrees Fahrenheit entering load center 118 to approximately sixty-five degrees Fahrenheit leaving load center 118. Additionally, psychometric chart 300 may be based on cooling tower 108 approach temperature. For example, cooling tower 108 may be a five degree Fahrenheit approach cooling tower. However, modifications may be made to psychometric chart 300, e.g., locations of free cooling line 308 and hybrid cooling line 310, based on a different designed cooling water 124 supply temperature, a different heat load at load center 118, and/or a different cooling tower 108 approach temperature. It is notable that the largest efficiencies and thus, greatest cost savings, may be accomplished with smaller cooling tower 108 approach temperatures, higher cooling water 124 supply temperatures, and/or larger temperature gains from the load.

In some embodiments, psychometric zone 302 may correspond to exterior air properties that enable free cooling system 102 to be the most efficient operating mode for cooling systems 180 and 280. For example, free cooling line 308 corresponds to wet bulb temperature of approximately fifty degrees Fahrenheit. Exterior air with properties at or below free cooling line 308, e.g., below or equal to wet bulb temperature of approximately fifty degrees Fahrenheit, may indicate that free cooling system 102 may be the most efficient Free cooling line 308 may be based on the amount of cooling that may be generated by cooling tower 108. Thus, in the present example, if free cooling line 308 is set at a wet bulb temperature of approximately five degrees Fahrenheit below the designed cooling water 124 temperature, then cooling tower 108 is able to lower the temperature of cooling water 124 entering cooling tower inlet 160 from approximately sixty-five degrees Fahrenheit to approximately fifty-five degrees Fahrenheit. Therefore, at wet bulb temperatures below approximately fifty degrees Fahrenheit, cooling system 180 or 280 may not require the use of chiller 116 and energy savings may be accomplished with free cooling system 102.

In some embodiments, psychometric zone 304 may correspond to exterior air properties that enable hybrid cooling system 104 to be the most efficient operating mode for cooling systems 180 and 280. For example, hybrid cooling line 310 corresponds to wet bulb temperature of approximately sixty degrees Fahrenheit. Thus, at free cooling line 308, cooling system 180 or 280 may transition from free cooling system 102 to hybrid cooling system 104. Tower valves 114 are configured such that cooling water 124 is directed from filtration subsystem 112 to evaporator 136. Center valves 120 are configured such that cooling water 124 is directed from load center 118 to condenser 138.

Exterior air with properties at or below hybrid cooling line 310 and above free cooling line 308, e.g., at wet bulb temperatures between approximately fifty degrees Fahrenheit and sixty degrees Fahrenheit, may indicate that hybrid cooling system 104 may be the most efficient. Hybrid cooling system 104 may maximize the available free cooling, e.g., operation of cooling tower 108, and minimize the energy use of chiller 116 by using part load conditions that may deliver better efficiency. For example, hybrid cooling system 104 may be most efficient when cooling tower 108 can produce between approximately fifty-five degrees Fahrenheit and approximately sixty-five degrees Fahrenheit cooling water 124 (assuming an approximately five degree Fahrenheit approach cooling tower). This amount of cooling corresponds to wet bulb temperatures between approximately fifty degrees Fahrenheit and sixty degrees Fahrenheit.

Accordingly, in the current example system, the load carried by chiller 116 may vary based on the exterior air wet bulb temperature. For example, at a wet bulb temperature less than or equal to approximately fifty degrees Fahrenheit, chiller 116 load may be approximately zero percent (e.g., free cooling system 102). At a wet bulb temperature of approximately fifty-one degrees Fahrenheit, chiller 116 load may be approximately ten percent (e.g., hybrid cooling system 104). The percentage load on chiller 116 may continue to increase as the wet bulb temperature increases until at approximately sixty degrees Fahrenheit, chiller 116 load may be approximately one hundred percent.

In some embodiments, psychometric zone 306 may correspond to exterior air properties that enable double loop cooling system 106 operating mode for cooling system 180. Exterior air with properties above hybrid cooling line 310, e.g., at wet bulb temperatures above approximately sixty degrees Fahrenheit, may indicate that double loop cooling system 106 as the option for cooling. For example, above hybrid cooling line 310, chiller 116 load may be approximately one hundred percent. Cooling system 180 may transition to first loop 106 a and second loop 106 b that utilizes secondary coolant 146.

Accordingly, energy efficiencies may occur through utilization of hybrid cooling system 104 at the appropriate wet bulb temperatures. As an example, Table 1 illustrates the approximate percentage load carried by chiller 116 at particular wet bulb temperatures that may be employed in operation of hybrid cooling system 104.

TABLE 1 Wet Bulb Temperature Load on Chiller 116 Less than or equal to 50 degrees Fahrenheit  0% 51 degrees Fahrenheit 10% 52 degrees Fahrenheit 20% 53 degrees Fahrenheit 30% 54 degrees Fahrenheit 40% 55 degrees Fahrenheit 50% 56 degrees Fahrenheit 60% 57 degrees Fahrenheit 70% 58 degrees Fahrenheit 80% 59 degrees Fahrenheit 90% Greater than or equal to 60 degrees Fahrenheit 100% 

In determining design parameters for cooling system 180 of FIG. 1 or 280 of FIG. 2, atmospheric data may be gathered for a particular location where the cooling system may be placed. For example, a wet bulb temperature profile may be gathered or generated for a particular city. The wet bulb temperature profile may include the average number of hours in a year at each wet bulb temperature.

First Example

As a first example, a wet bulb temperature profile for Denver, Colo., may indicate that on average Denver may not ever experience a wet bulb temperature above approximately sixty-nine degrees Fahrenheit. In such a location with low wet bulb temperatures, a cooling system similar to cooling configuration 200 shown with reference to FIG. 2 may be utilized. For example, a cooling system may have a load of approximately 800 tons, e.g., heat to be dissipated at load center 118. Cooling tower 108 may be designed as a five degree Fahrenheit approach cooling tower. For example, cooling tower 108 may be Marley cooling tower manufactured by SPX Cooling Technologies, Inc. (Overland Park, Kans.). Tower pump 110 may be a variable speed drive approximately fifty horsepower pump with a flow rate that may range from approximately 600 GPM to 1,300 GPM. Chiller 116 may be a 2,450 kW chiller manufactured by Trane, an Ingersoll Rand company (Davidson, N.C.). Chiller 116 flow rate may range from approximately 0.75 GPM/ton to 1.6 GPM/ton. Cooling water 124 supply temperature may be approximately fifty-five degrees Fahrenheit. The minimum chiller 116 lift may be approximately twelve degrees Fahrenheit.

During operation of the current example, a psychometric chart, such as psychometric chart 300, for the designed system may place free cooling line 308 at approximately fifty-one degrees. The designed system may place hybrid cooling line 310 at approximately sixty degrees Fahrenheit. For approximately seventy-one percent of the hours in each year, the wet bulb temperature may be lower than approximately fifty-one degrees Fahrenheit. Thus, cooling system 280 may be configured to operate free cooling system 102. Tower valve 114 and center valve 120 may be positioned to bypass chiller 116 in operation of free cooling system 102.

For an additional approximately twenty-nine percent of the hours in each year, the wet bulb temperature may be lower than approximately sixty-five degrees Fahrenheit. Hybrid cooling system 104 may be the most efficient mode to operate at these wet bulb temperatures. As such, the valves may be reconfigured to direct cooling water 124 to chiller 116 and chiller 116 may be started. For example, tower valve 114 may be positioned to direct flow to evaporator 136 and center valve 120 may be positioned to direct flow to condenser 138.

In the current example, the location may experience only approximately eleven hours per year with a wet bulb temperature over approximately sixty-five degrees Fahrenheit. For these few hours, rather than installing a double loop cooling system, which may require a separate pump and additional valves, hybrid cooling system 104 may be extended to these temperatures by decreasing the cooling water flow. For example, the pump flow rate may be decreased from approximately 1,300 GPM to approximately 1,000 GPM.

Without implementation of free cooling system 102 and hybrid cooling system 104, the chiller may run approximately 800 tons of cooling year round (8,760 hours) using a standard double loop configuration consuming approximately 3,611,047 kilowatt-hours of energy. Using the combined free cooling system 102 and hybrid cooling system 104 systems the resultant annual energy consumption is approximately 701,808 kilowatt-hours of energy an approximately eighty-one percent (81%) decrease in cooling consumption and cost.

Second Example

As a second example, a wet bulb temperature profile for Boston, Mass., may indicate that on average Boston may experience wet bulb temperatures as high as approximately seventy-seven degrees Fahrenheit. In such a location with relatively high wet bulb temperatures, a cooling system similar to cooling configuration 100 shown with reference to FIG. 1 may be utilized. For example, a cooling system may have a load of approximately 800 tons, e.g., heat to be dissipated at load center 118. Cooling tower 108 may be designed as a five degree Fahrenheit approach cooling tower. For example, cooling tower 108 may be Marley cooling tower manufactured by SPX Cooling Technologies, Inc. (Overland Park, Kans.). Tower pump 110 and system pump 122 may be variable speed drive approximately fifty horsepower pumps with a flow rate that may range from approximately 600 GPM to 1,000 GPM. Chiller 116 may be a 2,450 kW chiller manufactured by Trane, an Ingersoll Rand company (Davidson, N.C.). Chiller 116 flow rate may range from approximately 0.75 GPM/ton to 1.3 GPM/ton. Cooling water 124 supply temperature may be approximately fifty-five degrees Fahrenheit. The minimum chiller 116 lift may be approximately twelve degrees Fahrenheit.

During operation of the current example, a psychometric chart, such as psychometric chart 300, for the designed system may place free cooling line 308 at approximately fifty-one degrees. The designed system may place hybrid cooling line 310 at approximately sixty degrees Fahrenheit. For approximately sixty-one percent of the hours in each year, the wet bulb temperature may be lower than approximately fifty-one degrees Fahrenheit. Thus, cooling system 180 may be configured to operate free cooling system 102. Tower valves 114 and center valves 120 may be positioned to bypass the chiller in operation of free cooling system 102.

For an additional approximately twenty-nine percent of the hours in each year, the wet bulb temperature may be lower than approximately sixty-five degrees Fahrenheit. Hybrid cooling system 104 may be the most efficient mode to operate at these wet bulb temperatures. As such, the valves may be reconfigured to direct cooling water 124 to chiller 116 and chiller 116 may be started. For example, tower valves 114 may be positioned to direct flow to evaporator 136 and center valves 120 may be positioned to direct flow to condenser 138.

In the current example, the location may experience approximately ten percent of the hours in each year with a wet bulb temperature over approximately sixty-five degrees Fahrenheit. Double loop cooling system 106 may be the mode to operate at these wet bulb temperatures. As such, first loop 106 a may be configured so that tower valves 114 may direct cooling water 124 to condenser 138. Second loop 106 b may be configured so that center valves 120 direct secondary coolant 146 to evaporator 136. System pump 122 may also be started in the transition to double loop cooling system 106.

In the current example, the wet-bulb temperature profile includes hours in all three modes of cooling system 180 operation. For example, there may be approximately 416 hours of double loop cooling system 106 operation, 2,994 hours of hybrid cooling system 104 operation, and 5,350 hours of free cooling system 102 operation. A typical system may run approximately 800 tons of cooling year round (8,760 hours) using double loop configuration exclusively and consume approximately 3,611,047 kilowatt-hours of energy. Using the combined free cooling system 102, hybrid cooling system 104 and double loop cooling system 106, the resultant annual energy consumption may be approximately 1,085,699 kilowatt-hours of energy resulting in an approximately seventy percent (70%) decrease in cooling consumption and cost.

Third Example

As a third example, a wet bulb temperature profile for Dallas, Tex., may indicate that on average Dallas may experience wet bulb temperatures as high as approximately eighty-three degrees Fahrenheit. In such a location with relatively high wet bulb temperatures, a cooling system similar to cooling configuration 100 shown with reference to FIG. 1 may be utilized. For example, a cooling system may have a load of approximately 800 tons, e.g., heat to be dissipated at load center 118. Cooling tower 108 may be designed as a five degree Fahrenheit approach cooling tower. For example, cooling tower 108 may be Marley cooling tower manufactured by SPX Cooling Technologies, Inc. (Overland Park, Kans.). Tower pump 110 and system pump 122 may be variable speed drive approximately fifty horsepower pumps with a flow rate that may range from approximately 600 GPM to 1,000 GPM. Chiller 116 may be a 2,450 kW chiller manufactured by Trane, an Ingersoll Rand company (Davidson, N.C.). Chiller 116 flow rate may range from approximately 0.75 GPM/ton to 1.3 GPM/ton. Cooling water 124 supply temperature may be approximately fifty-five degrees Fahrenheit. The minimum chiller 116 lift may be approximately twelve degrees Fahrenheit.

During operation of the current example, a psychometric chart, such as psychometric chart 300, for the designed system may place free cooling line 308 at approximately fifty-one degrees. The designed system may place hybrid cooling line 310 at approximately sixty degrees Fahrenheit. For approximately thirty-four percent of the hours in each year, the wet bulb temperature may be lower than approximately fifty-one degrees Fahrenheit. Thus, cooling system 180 may be configured to operate free cooling system 102. Tower valves 114 and center valves 120 may be positioned to bypass the chiller in operation of free cooling system 102.

For an additional approximately twenty-eight percent of the hours in each year, the wet bulb temperature may be lower than approximately sixty-five degrees Fahrenheit. Hybrid cooling system 104 may be the most efficient mode to operate at these wet bulb temperatures. As such, the valves may be reconfigured to direct cooling water 124 to chiller 116 and chiller 116 may be started. For example, tower valves 114 may be positioned to direct flow to evaporator 136 and center valves 120 may be positioned to direct flow to condenser 138.

In the current example, the location may experience approximately thirty-eight percent of the hours in each year with a wet bulb temperature over approximately sixty-five degrees Fahrenheit. Double loop cooling system 106 may be the mode to operate at these wet bulb temperatures. As such, first loop 106 a may be configured so that tower valves 114 may direct cooling water 124 to condenser 138. Second loop 106 b may be configured so that center valves 120 direct secondary coolant 146 to evaporator 136. System pump 122 may also be started in the transition to double loop cooling system 106.

In the current example, the wet-bulb temperature profile includes hours in all three modes of cooling system 180 operation. For example, there may be approximately 2,589 hours of double loop cooling system 106 operation, 3,155 hours of hybrid cooling system 104 operation, and 3,016 hours of free cooling system 102 operation. A typical system may run approximately 800 tons of cooling year round (8,760 hours) using a standard double loop configuration consuming approximately 3,611,047 kilowatt-hours of energy. Using the combined free cooling system 102, hybrid cooling system 104 and double loop cooling system 106, the resultant annual energy consumption may be approximately 1,993,156 kilowatt-hours of energy resulting in an approximately forty-five percent (45%) decrease in cooling consumption and cost.

FIG. 4 illustrates a flow chart for an example method for cooling system transitions using hybrid cooling systems, in accordance with certain embodiments of the present disclosure. The steps of method 600 may be performed by various computer programs, models or any combination thereof. The programs and models may include instructions stored on a computer-readable medium that are operable to perform, when executed, one or more of the steps described below. The computer-readable medium may include any system, apparatus or device configured to store and/or retrieve programs or instructions such as a microprocessor, a memory, a disk controller, a compact disc, flash memory or any other suitable device. The programs and models may be configured to direct a processor or other suitable unit to retrieve and/or execute the instructions from the computer-readable medium. For example, method 400 may be executed by processing system 126, an operator of the cooling system, and/or other suitable source. For illustrative purposes, method 400 may be described with respect to cooling system 180 of FIG. 1; however, method 400 may be used for cooling system transitions using hybrid cooling system of any suitable configuration.

Although FIG. 4 discloses a particular number of steps to be taken with respect to method 400, method 400 may be executed with greater or lesser steps than those depicted in FIG. 4. In addition, although FIG. 4 discloses a certain order of steps to be taken with respect to method 400, the steps comprising method 400 may be completed in any suitable order.

At step 405, method 400 determines the temperature of cooling water that exits a cooling tower, e.g., T_(CT). For example, with reference to FIG. 1, a temperature sensor senses the temperature of cooling water 124 as cooling water 124 exits cooling tower 108 at cooling tower outlet 158. Processing system 126 receives the sensed temperature or T_(CT).

At step 410, method 400 determines if the sensed temperature of cooling water exiting the cooling tower is greater than a preset temperature, T₁. For example, processing system 126 determines if T_(CT) may be greater than T₁. T₁ is based on design considerations, atmospheric conditions, sizes and loads on components in the cooling system, and/or any other suitable factor. T₁ may be the temperature at which it becomes more efficient to operate cooling system as a hybrid cooling system in place of a free cooling system. For example, with reference to FIG. 1, T₁ may be set at approximately fifty-five degrees Fahrenheit. In this example, when the cooling water exiting temperature, T_(CT), is less than or equal to approximately fifty-five degrees Fahrenheit, then method 400 proceeds to step 415. If T_(CT) is greater than approximately fifty-five degrees Fahrenheit, method 400 proceeds to step 425.

At step 415, method 400 is configured to operate a free cooling system and configure the tower valves to direct the cooling water to the load center. For example, with reference to FIG. 1, processing system 126 electronically configures tower valve 164 a to direct cooling water 124 from filtration subsystem 112 to load center 118.

At step 420, method 400 configures the center valves to direct the cooling water to the cooling tower. For example, processing system 126 electronically configures center valve 166 a to direct cooling water 124 from load center 118 to cooling tower 108. After step 420, method 400 returns to step 405.

At step 425, method 400 determines if the sensed temperature of cooling water exiting the cooling tower is greater than a preset temperature, T₂. For example, processing system 126 determines if T_(CT) may be greater than T₂. T₂ may be based on design considerations, atmospheric conditions, sizes and loads on components in the cooling system, and/or any other suitable factor. T₂ may be the temperature at which it becomes necessary to operate the cooling system as a double loop cooling system in place of a hybrid cooling system. For example, with reference to FIG. 1, T₂ is set at approximately sixty-five degrees Fahrenheit. In this example, when the cooling water exiting temperature, T_(CT), is below or equal to approximately sixty-five degrees Fahrenheit, then method 400 proceeds to step 430. If T_(CT) is greater than approximately sixty-five degrees Fahrenheit, method 400 proceeds to step 440.

At step 430, method 400 is configured to operate a hybrid cooling system and configures the tower valves to direct the cooling water to the evaporator. For example, with reference to FIG. 1, processing system 126 electronically configures tower valve 164 a to direct cooling water 124 from filtration subsystem 112 to tower valve 164 b. Processing system 126 further electronically configures tower valve 164 b to direct cooling water 124 from tower valve 164 a to evaporator 136.

At step 435, method 400 configures the center valves to direct the cooling water to the condenser. For example, processing system 126 electronically configures center valve 166 a to direct cooling water 124 from load center 118 to center valve 166 b. Processing system 126 further electronically configures center valve 166 b to direct cooling water 124 from load center 118 to condenser 138. After step 435, method 400 returns to step 405.

At step 440, method 400 is configured to operate a double loop cooling system and configures the tower valves to direct the cooling water to the condenser. For example, with reference to FIG. 1, processing system 126 electronically configures tower valve 164 a to direct cooling water 124 from filtration subsystem 112 to tower valve 164 b. Processing system 126 further electronically configures tower valve 164 b to direct cooling water 124 from tower valve 164 a to condenser 138.

At step 445, method 400 configures the center valves to direct a secondary coolant to the evaporator. For example, processing system 126 electronically configures center valve 166 a to direct secondary fluid 146 from load center 118 to center valve 166 b. Processing system 126 further electronically configures center valve 166 b to direct coolant 146 from center valve 166 a to evaporator 136. After step 445, method 400 returns to step 405.

Modifications, additions, or omissions may be made to method 400 without departing from the scope of the present disclosure and invention. For example, the order of the steps may be performed in a different manner than that described and some steps may be performed at the same time. For example, step 425 and step 410 may be performed simultaneously. Additionally, each individual step may include additional steps without departing from the scope of the present disclosure. For example, step 415 may be preformed before or after step 410 without departing from the scope of the present disclosure.

Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alternations can be made herein without departing from the spirit and scope of the invention which is solely defined by the following claims. 

What is claimed is:
 1. A hybrid cooling system comprising: a load center including a load center inlet and a load center outlet; a condenser including a condenser inlet and a condenser outlet, the load center outlet fluidically coupled to the condenser inlet; a cooling tower including a cooling tower inlet and a cooling tower outlet, the condenser outlet fluidically coupled to the cooling tower inlet; and an evaporator including an evaporator inlet and an evaporator outlet, the cooling tower outlet fluidically coupled to the evaporator inlet, the evaporator outlet fluidically coupled to the load center inlet.
 2. A system according to claim 1, further comprising a first valve configured to direct a coolant from the cooling tower outlet to the evaporator inlet and a second valve configured to direct the coolant from the load center outlet to the condenser inlet.
 3. A system according to claim 1, further comprising a variable speed pump configured to circulate a coolant and maintain a flow rate of the coolant.
 4. A system according to claim 1, further comprising a first temperature sensor to monitor a temperature of a coolant that exits the cooling tower outlet.
 5. A system according to claim 4, wherein the cooling tower includes a variable speed fan configured to adjust fan speed based on the temperature of the coolant that exits the cooling tower outlet.
 6. A system according to claim 1, wherein the cooling tower includes a variable speed fan configured to adjust fan speed based on a wet bulb temperature of an exterior atmosphere.
 7. A system according to claim 1, further comprising a coolant that is cooling water.
 8. A cooling system comprising: a load center including a load center inlet and a load center outlet; a condenser including a condenser inlet and a condenser outlet; a cooling tower including a cooling tower inlet and a cooling tower outlet; an evaporator including an evaporator inlet and an evaporator outlet; a temperature sensor configured to measure a temperature of a first coolant that exits the cooling tower outlet; based on the measured temperature being greater than a first designed temperature, the first coolant directed from the load center outlet to the condenser inlet, from the condenser outlet to the cooling tower inlet, from the cooling tower outlet to the evaporator inlet; and from the evaporator outlet to the load center inlet; and based on the measured temperature being less than or equal to the first designed temperature, the first coolant directed from the load center outlet to the cooling tower inlet, and from the cooling tower outlet to the load center inlet.
 9. A system according to claim 8, further comprising: based on the measured temperature being greater than a second designed temperature: the first coolant directed from the cooling tower outlet to the condenser inlet and from the condenser outlet to the cooling tower inlet; and a second coolant directed from the evaporator outlet to the load center inlet and from the load center outlet to the evaporator inlet.
 10. A system according to claim 8, further comprising: a first valve configured to direct the first coolant from the cooling tower outlet to the evaporator inlet or the load center inlet; and a second valve configured to direct the first coolant from the load center outlet to the condenser inlet or the cooling tower inlet.
 11. A system according to claim 9, further comprising: a third valve configured to direct the first coolant from the cooling tower outlet to the condenser inlet; and a fourth valve configured to direct the second coolant from the load center outlet to the evaporator inlet.
 12. A system according to claim 8, further comprising a variable speed pump configured to circulate the first coolant and maintain a flow rate of the first coolant.
 13. A system according to claim 9, further comprising a second variable speed pump configured to circulate the second coolant and maintain a flow rate of the second coolant.
 14. A system according to claim 8, further comprising a variable speed fan operating based on the measured temperature.
 15. A system according to claim 8, further comprising: a temperature sensor configured to measure a wet bulb temperature; and a variable speed fan operating based on the measured wet bulb temperature.
 16. A method for a cooling system comprising: measuring a cooling tower exit temperature of a first coolant; based on the measured temperature being greater than a first designed temperature, directing the first coolant from a load center outlet to a condenser inlet, from a condenser outlet to a cooling tower inlet, from a cooling tower outlet to an evaporator inlet; and from an evaporator outlet to a load center inlet; and based on the measured temperature being less than or equal to the first designed temperature, directing the first coolant from the load center outlet to the cooling tower inlet, and from the cooling tower outlet to the load center inlet.
 17. A method according to claim 16, further comprising: based on the measured temperature being greater than a second designed temperature: directing the first coolant from the cooling tower outlet to the condenser inlet and from the condenser outlet to the cooling tower inlet; and directing a second coolant from the evaporator outlet to the load center inlet and from the load center outlet to the evaporator inlet.
 18. A method according to claim 16, further comprising: configuring a first valve to direct the first coolant from the cooling tower outlet to the evaporator inlet or the load center inlet; and configuring a second valve to direct the first coolant from the load center outlet to the condenser inlet or the cooling tower inlet.
 19. A method according to claim 17, further comprising: configuring a third valve to direct the first coolant from the cooling tower outlet to the condenser inlet; and configuring a fourth valve to direct the second coolant from the load center outlet to the evaporator inlet.
 20. A method according to claim 16, further comprising configuring a variable speed pump to circulate the first coolant and maintain a flow rate of the first coolant. 